1. Field of the Invention
The present invention relates to an image reading apparatus and an image reading method, and particularly to an image reading apparatus and image reading method for reading images recorded on a photographic photosensitive material such as a photographic film.
2. Description of the Related Art
A type of conventional laboratory system for processing an image recorded on a photographic photosensitive material such as a photographic film (hereafter, referred to as xe2x80x9cphotographic filmxe2x80x9d) exists in which, firstly, a comparatively high speed, low detail preparatory reading (hereafter referred to as a xe2x80x9cprescanxe2x80x9d) is performed to read the image. Next, on the basis of the image data obtained from the prescan, the photometric condition for when a comparatively low speed, high detail main reading (hereafter referred to as a xe2x80x9cfine scanxe2x80x9d) is performed to read the image, and the processing condition of the image processing performed on the image data obtained from the fine scan are determined. The fine scan is performed in accordance with the determined photometric condition and image processing is performed on the image data obtained from the fine scan in accordance with the above-described determined processing condition.
In this type of laboratory system, two photometric systems, each provided with CCD sensor for reading the image are provided in the image reading apparatus used to read an image recorded on a photographic film with the aim of speeding up the image reading process. One photometric system is used for performing the prescan and the other photometric system is used for performing the fine scan thus allowing the prescan and fine scan to be performed in parallel.
However, in the above-described image reading apparatus equipped with two photometric systems, in both the prescan and the fine scan, a charge accumulation time of the CCD sensor and the amount of light irradiated onto the image to be read are changed in accordance with the type of the image to be read and so on. Therefore, drawbacks exist in that the overall structure of the image reading apparatus is complex and the cost thereof is high. This is explained in more detail below.
FIG. 11 is a graph showing an example of the relationship between the negative image density (input density value) and the photometric value (output density value) for a negative image from which the photomertic measurement is performed by a CCD sensor.
As is shown in FIG. 11, the relationship between the negative image density and the photometric value is ideally a straight line with a gradient of 45xc2x0. However, in actuality, because of the effect of offset C with respect to the input density value, the linearity of the line cannot be maintained in the high density region. When various high-accuracy processings are performed using the photometric values obtained using the CCD sensor, only the region where the line is highly linear, i.e. excluding the high-density region, can be used, leading to a narrow dynamic range.
Two methods can be considered in order to increase the linearity of the high-density region. In one method, the amount of light irradiated onto the negative image is increased, while in the other method, the charge accumulation time is changed. The above described image reading apparatus equipped with two photometric systems, however, is structured so that the amount of light and the charge accumulation time can be adjusted for each photometric system. Therefore, the structure of each photometric system is complex and the cost of the overall device is high.
The present invention was conceived in order to solve the above-described drawbacks and the objective thereof is to provide an image reading apparatus and an image reading method which can perform a rapid image reading at a low cost.
In order to achieve the above objective, the image reading apparatus according to the first aspect of the present invention comprises:
transporting means for transporting a photographic photosensitive material on which an image is recorded in such a way that the image passes in sequence over a first reading position and a second reading position;
a first photometric system which is provided with a first light source for irradiating light onto the image at the first image reading position and which is also provided with a first image sensor for reading with fixed photometric condition the image and outputting the image as image data on the basis of one of the light transmitted through the image or the light reflected from the image;
a second photometric system which is provided with a second light source for irradiating light onto the image at the second image reading position and which is also provided with a charge accumulation-type second image sensor for reading the image and outputting the image as image data on the basis of one of the light transmitted through the image or the light reflected from the image; and
control means for controlling the second photometric system in such a way that the image is read by changing at least one of amount of light irradiated from the second light source and a charge accumulation time of the second image sensor on the basis of the image data output from the first image sensor.
According to the image reading apparatus of the first aspect of the present invention, a photographic photosensitive material having an image recorded thereon is transported by the transporting means so that the image passes in sequence through the first reading position and the second reading position.
Light is irradiated onto the image at the first reading position by the first light source provided in the first photometric system. The image is then read by the first image sensor provided in the first photometric system on the basis of the light transmitted through the image or the light reflected from the image with the photometric condition in a fixed state, and the image is output as image data. Light is then irradiated onto the image at the second reading position by the second light source provided in the second photometric system. The image is then read by the charge accumulation-type second image sensor provided in the second photometric system on the basis of the light transmitted through the image or the light reflected from the image, and the image is output as image data. Note that the type of sensor used as the above-described first image sensor includes all types of photoelectrically convertible sensors such as a silicon photodiode in addition to charge accumulation-type image sensors. While the type of sensor used as the second image sensor includes CCD-type sensors and MOS-type sensors. Moreover, the amount of light irradiated from the above first light source and the charge accumulation time when the above first image sensor is a charge accumulation-type sensor are included in the photometric condition.
At this stage, when the image is being read by the above-described second photometric system, the second photometric system is controlled so that the image is read with at least one of the amount of light irradiated from the second light source and the charge accumulation time of the second image sensor being changed by the control means on the basis of the image data output from the first image sensor.
Namely, for example, as was mentioned above, when the image data obtained from the prescan is used for determining the photometric condition and so on for performing the fine scan, even if the linearity of the above image data is comparatively low there is no problem, however, the image data obtained from the fine scan is used for outputting an actual image which means that a high linearity is required.
Accordingly, the prescan can be performed by the first photometric system of the present invention in which an image is read with the above-described photometric condition in a fixed state. By structuring the first photometric system in this way, the structure of the first photometric system can be simplified (i.e. be of a lesser quality than the second photometric system)
In this way, according to the image reading apparatus of the first aspect of the present invention, because the photometric condition provided in the first photometric system are fixed, the structure of the first photometric system can be simplified in comparison to a structure in which the photometric condition are adjusted. Thus the effect of a reduction in the overall cost of the device is achieved.
In the image reading apparatus according to the second aspect of the present invention, the control means according to the first aspect of the present invention performs, the control means performs:
at least one of: the detection of the position of the image; the detection of the size of the image; the detection of the DX code when the DX code is affixed to the photographic photosensitive material; the detection of the frame number when the frame number is affixed to the photographic photosensitive material; the determination of whether or not the image is an unneeded image; and the determining of the photometric condition of the second photometric system on the basis of the image data output from the first photometric system, and;
at least one of: the determining of the processing condition for the image processing for the image data output from the second photometric system; and the inspection of the image using the image data output from the second photometric system on the basis of the image data output from the second photometric system.
According to the image reading apparatus of the second aspect of the present invention, the control means performs: at least one of: the detection of the position of the image; the detection of the size of the image; the detection of the DX code when the DX code is affixed to the photographic photosensitive material; the detection of the frame number when the frame number is affixed to the photographic photosensitive material; the determination of whether or not the image is an unneeded image; and the determining of the photometric condition of the second photometric system on the basis of the image data output from the first photometric system, and; at least one of: the determining of the processing condition for the image processing for the image data output from the second photometric system; and the inspection of the image using the image data output from the second photometric system on the basis of the image data output from the second photometric system.
The above-mentioned DX code is a widely used code indicating the maker and sensitivity of the photographic photosensitive material. Unneeded images include images in which the focus on the subject of the photograph is blurred (commonly known as xe2x80x9cblurred focussingxe2x80x9d), and images which are extremely under-exposed or extremely over-exposed to the extent that the subject of the image is unidentifiable. The photometric processing condition for the second photometric system include the charge accumulation time when the image is read by the second image sensor and the amount of light from the second light source. The image processing condition include the image enlargement/reduction ratio, hypertone and hyper-sharpness image processing condition, and gradation conversion conditions. The image inspection (examination) is an examination of the image data by an operator who refers to the image which is displayed on a display means such as a CRT display using the image data.
In the image reading apparatus according to the second aspect of the present invention, because the above image position detection, image size detection, DX code detection, frame number detection, unneeded image determination, and second photometric system photometric condition determination can all be performed using comparatively low precision image data, they are performed using the image data obtained by the first photometric system having fixed photometric condition. Moreover, because the determining of the image processing condition for the image data output from the second photometric system and the examining of the image using the image data output from the second photometric system are preferably performed using comparatively high precision image data, they are performed using the image data obtained by the second image sensor having a variable charge accumulation time.
In this way, processing which can be performed using comparatively low precision image data is performed on the basis of the image data obtained by the first photometric system. Only processing which is preferably performed using comparatively high precision image data is performed on the basis of image data obtained by the second photometric system. Therefore, the overall image reading efficiency of the device can be improved and the speed of the image reading can be increased.
According to the image reading apparatus according to the third aspect of the present invention, in the image reading apparatus of the second aspect of the present invention, there is further provided a storage means in which the image data output from the second photometric system is stored until at least one of the determining of the processing condition for the image processing for the image data output from the second photometric system and the examination of the image using the image data output from the second photometric system is completed.
According to the image reading apparatus of the third aspect of the present invention, the image data output from the second photometric system, in the image reading apparatus according to the second aspect of the present invention, is stored in the storage means until at least one of the determining by the control means of the image processing condition for the image data output from the second photometric system and the examining by the control means of the image using the image data output from the second photometric system is completed.
In this way, according to the image reading apparatus of the third aspect of the present invention, the same effect as in the second aspect of the present invention can be achieved. Because the image data output from the second photometric system is stored in the storage means until at least one of the determining by the control means of the image processing condition for the image data output from the second photometric system and the examining by the control means of the image using the image data output from the second photometric system has been completed, the operation of reading the image by the second photometric system and at least one of the determining by the control means of the image processing condition for the image data output from the second photometric system and the examining by the control means of the image using the image data output from the second photometric system can be performed in parallel and the speed at which the image is read can be increased.
Note that, as in the fourth aspect of the present invention, in the image reading apparatus according to the first through third aspects of the present invention, an area sensor can be used for the first image sensor and a line sensor can be used for the second image sensor.
Namely, when, for example, the afore-mentioned prescan is performed using the first photometric system and the fine scan is performed using the second photometric system, as is explained above, during the prescan the image is read at comparatively high speed and at a low level of precision while during the fine scan the image is read at comparatively low speed and at a high level of precision. Therefore, in comparison with the second image sensor, a low resolution area sensor can be used for the first image sensor which allows a low cost sensor to be used for the first image sensor enabling the overall cost of the device to be reduced.
In the image reading method according to the fifth aspect of the present invention,
a photographic photosensitive material on which an image is recorded is transported in such a way that the image passes in sequence over a first reading position and a second reading position;
light from a first light source is irradiated onto the image at the first image reading position, and the image is read by a first image sensor with fixed photometric condition and output as image data on the basis of one of the light transmitted through the image or the light reflected from the image;
at least one of amount of light irradiated onto the image from a second light source and a charge accumulation time of a charge accumulation-type second image sensor are changed on the basis of the output image data, and light from the second light source is irradiated onto the image at the second image reading position and the image is read by the second image sensor and output as image data on the basis of one of the light transmitted through the image or the light reflected by the image.
In this way, according to the image reading method of the fifth aspect of the present invention, because the image recorded on the photographic photosensitive material is read by the first image sensor with the photometric condition in a fixed state, in the same way as in the first aspect of the present invention, compared to when the photometric condition are adjusted, the structure of the device can be simplified and the cost of realizing the present invention is reduced.